IEBCOPY cannot increase the number of directory blocks in a partitioned data set. (A PDSE directory automatically expands as needed.) If you are not sure there will be enough directory blocks in the output partitioned data set you are merging to, then you should expand the output data set directory space before beginning the merge operation.

Use IEHLIST to determine how much directory space remains in a partitioned data set. If more blocks are needed, this procedure will extend most data sets:

1. Rename the data set.
2. Allocate a new data set with enough space and directory blocks.
3. Copy the renamed data set to the newly allocated data set.
4. Delete the renamed data set (or save it as a backup).